1. Field of the Invention
The present invention relates to a novel and useful phenoxazine derivative having prophylactic and therapeutic effects on cataracts, a process for production thereof, and an anticataract composition containing said phenoxazine derivative.
2. Description of the Prior Art
While cataracts is a disease arising from opacification of the lens, its pathogenesis remains to fully elucidated as yet. It follows, then, that a prophylactic and therapeutic pharmacotherapy has not been established for the disease. Under the circumstances, 1-hydroxy-5-oxo-5H-pyrido[3,2a]phenoxazine-3-carboxylic acid and its salt have been accredited with the reputation of being the most effective of all the drugs available so far for cataracts, and are being used widely, particularly as agents for arresting the progression of early-stage senile cataracts, with successful results.
Under the circumstances, on the thought that the efficacy of these compounds might be enhanced if the rate of transfer of the compound to tissues be increased, the present inventors synthesized a series of compounds structurally related to the above known compounds and ultimately succeeded in the synthesis of ester derivatives meeting the above-mentioned objective. The present invention has been developed on the basis of the above accomplishment.